This invention relates to a method of securing a metallic insert to a molded plastic body and more particularly to a method of securing metallic terminal electrodes to a molded ignition distributor cap and to a distributor cap made by the method of this invention.
In order to avoid the difficulties associated with molding plastic material about metallic parts, such as the molding of a distributor cap to the terminals of the cap, it has been proposed to mold a plastic part with holes or openings and then fit the metal part to the opening. The metal part must be retained by the plastic part and various arrangements for accomplishing this are disclosed in the U.S. Pat. Nos. 4,338,895 to Lennis et al.; 3,951,508 to Farrer et al.; 3,591,736 to Morgan et al. and 2,304,036 to Tegarty.
In the above-referenced Lennis et al. patent a distributor cap is molded to such a configuration as to provide slots or openings in the towers of the cap and then terminal electrodes are fitted to the openings. The outer terminals of the distributor cap are fixed to the cap by legs on the terminals that are flexed to a locked position when a terminal is inserted into a cap opening. The center electrode is retained by yieldable fingers that are integral with the cap.
In the above-referenced Farrer et al. patent terminals are inserted into bores of the towers of the molded distributor cap. The terminals are retained in the cap by slipping a bored male terminal member over an end of the terminal. The exterior end of the terminal is then rolled or spun over the male terminal member.
In the above-referenced Morgan et al. patent the terminals are fitted to openings in the distributor cap immediately following the hot molding of the cap.
In the above-referenced Tegarty patent a metal insert is fixed to a molded plastic part by inserting the metal insert into an opening or bore formed in the plastic part. The metal part has ratchet-like teeth that cause the plastic material to cold flow behind the teeth as the metal part is inserted into the bore.